Try as I might, I can't seem to get this set to behave for the camera. So please excuse the wrinkles! The fabric is very soft and would really look much better being worn!
The top is 100% cotton flannel and closes with a zipper in the back.  It's trimmed with the same little flower buttons, embroidery and 
yo-yos that are on the pants.  The pants are also 100% cotton and are made from velveteen...also known as no-wale corduroy.  I looked it up and tried unsuccessfully to find the difference between the two.  So call it what you will, it's still cotton!
This set is a size 18 months. 
Machine wash cold, tumble dry low.

Flannel and velveteen set, size 18m, $40 including shipping.